Merit Grows Little By Little:
Some tend to think that virtue can be taken lightly, and that virtue practiced is not likely to bring about any spectacular good results. This view is not quite correct. The good done by an individual accumulates little by little. The process is very much like the filling of a water-pot, drop by drop. As time goes on, the little acts of virtue accumulate, until the doer of good is totally filled with it.
~ The Buddha ~
PS : The same can be said of vices also . Those who indulge in it bit by bit may feel they are doing no wrong and no one notices the same and they can escape till one day it becomes a tsunami and consumes them in one stroke .